The Collaborative International Dictionary of English v.0.48:

Wiver \Wiv"er\, Wivern \Wiv"ern\, n. [OE. wivere a serpent, OF.
   wivre, guivre, F. givre, guivre, wiver, from L. vipera;
   probably influenced by OHG. wipera, from the Latin. See
   Viper, and cf. Weever.]
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   1. (Her.) A fabulous two-legged, winged creature, like a
      cockatrice, but having the head of a dragon, and without
      spurs. [Written also wyvern.]
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            The jargon of heraldry, its griffins, its mold
            warps, its wiverns, and its dragons.  --Sir W.
                                                  Scott.
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   2. (Zool.) The weever.
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